This project is concerned with the physiology of vertebrate photoreceptors, the processing of visual information within the retina, and the mechanisms underlying retinal responses. Both intra- and extracellular recordings will be made from photoreceptors and retinal neurons in selected species. Specific problems currently under investigation include: 1) The role of potassium in modulating retinal sensitivity in the skate retina; 2) The effects of neurotransmitters and their analogues on retinal neurons in amphibians; 3) The origin and functional significance of the electroretinogram oscillatory potentials. BIBLIOGRAPHIC REFERENCES: Kleinschmidt, Jochen, and John E. Dowling, 1975. Intracellular Recordings from Gecko Photoreceptors during Light and Dark Adaptation, J. Gen. Physiol., 66, 617-648. Pepperberg, David R., Mark Lurie, Paul K. Brown, and John E. Dowling, 1976. Visual Adaptation: Effects of Externally Applied Retinal on the Light-Adapted, Isolated Skate Retina, Science 191, 394-396.